myxoma may be tethered in sucha way that it follows the flow from the LA into the LV. The myxoma then appears as a structure posterior to the anterior mitral leaflet and, depending on its density maybe thought to be a thickening of the mitral leaflet. 2D echo helps to define the structure

Of the following, which is NOT a criterion for idopathic hypertrophic subarotic stenosis(IHSS)?